The invention relates to a pianoforte instrument, in particular a piano, with a base and with several bearings for support on a floor.
Pianoforte instruments, in particular pianos, in addition to the primary elements for producing sound, such as, for instance, the keyboard, the strings, and the soundboard, also have a housing with bottom frame and top frame, in which these elements are arranged or to which they are attached.
Particularly for pianos, such a housing with bottom frame and top frame, in which the soundboard and the strings are arranged, rests on a base with a baseboard. Placed on the top frame is the keyboard with a keybed, a lock rail, and a fallboard. The user must be able to operate the keyboard. It therefore projects forward from the body or the bottom frame. In front of the bottom frame below the keyboard is a free space, in which the knees and lower legs of the pianist are situated when the piano is played, while the hands of the pianist move on and over the keys of the keyboard also when the piano is played.
The keyboard is additionally supported on either side of the pianist. Provided for this purpose are consoles, each of which is supported on a foot. The feet are joined to the baseboard.
An aspect of pianoforte instruments that has received too little attention lies in the problem posed by an uneven underlying surface. In the case of grand pianos, this aspect is addressed in that grand pianos stand on three bearings, thereby permitting a three-point bearing, which is stable even for uneven floors.
A similar solution is proposed, for instance, in US 2009/0120264 A1, which describes a pianolike electronic musical instrument, in which, quite intentionally, besides two front bearing legs, a third rearward bearing leg, turned away from the player, is provided so as, in turn, to create a stable three-point bearing.
However, similar concepts are also known already from older publications, such as U.S. Pat. No. 2,486,354, where, in order to provide a solution for stability and for compensation for uneven floors, the entire piano is constructed on a platelike base, which, in turn, rests once again with three bearings on the floor.
For pianos and comparable pianoforte instruments, which predominantly rest with four bearing points on the floor, generally in practice makeshift washers are placed underneath one of the bearings so as to prevent by eye at least a tilting of the piano.
This problem is all the more aggravating when the piano is to be placed at changing locations or even when only a change in position within a room or a hall is to be undertaken, in which case, owing to the inevitably existing slight differences in floor unevenness, a potential compensation found in one case is certainly inappropriate and has to be reselected and readjusted.
This is further complicated by the fact that, when the problem posed is subject to closer expert examination, preventing a tilting of the piano is not the concern or not the sole concern. It should be considered that quite substantial forces act in a piano, these forces arising not only due to the weight of the components, but also due to the fact that, owing to their tension, tensioned strings exert substantial forces on their fixing points and the soundboard. The tensile forces that can act in the instrument owing to the set of strings can amount to around 20 tons.
A nonuniform load on the different bearing points is accordingly transmitted to the strings, leading to a change in sound therein. This is an effect that is undesirable, especially for a pianoforte instrument. This effect also arises when the piano rests in place even without so-called tilting, but the bearings are subject to quite differing loads.